Head-to-head comparison of 18F-FAP-2286 PET/CT and 18F-FDG PET/CT in the diagnosis and staging of clear cell renal cell carcinoma: a prospective study

This research was designed to evaluate the diagnostic efficacy, lesion detection, and clinical management impact of 18F-FAP-2286 PET/CT versus 18F-FDG PET/CT in patients with clear cell renal cell carcinoma (ccRCC). Participants with confirmed or suspected ccRCC diagnoses were prospectively included in our study. All patients underwent 18F-FAP-2286 and 18F-FDG PET/CT. The evaluation of diagnostic performance was conducted utilizing pathology and clinical follow-up as the reference standards. The quantitative analysis included the SUVmax, TBR, FTV/MTV, and TLF/TLG. Twenty-two patients with initial stage (n = 20)/recurrent (n = 2) ccRCC underwent 18F-FAP-2286 and 18F-FDG PET/CT. Compared with 18F-FDG PET/CT, 18F-FAP-2286 PET/CT had a greater TBR for primary ccRCC lesions [2.8 (1.9–5.4) vs.1.6 (1.1–3.8); P = 0.019], whereas the SUVmax did not significantly differ [8.4 (4.7–17.2) vs.6.6 (4.9–19.4); P = 0.965]. With respect to metastatic lymph nodes, 18F-FAP-2286 PET/CT had a higher SUVmax [13.7 (10.8–18.3) vs. 11.0 (7.3–16.4); P = 0.043] and TBR [10.4 (8.0-13.3) vs. 5.7 (3.4–8.7); P<0.001]. For distant metastases, the detection rates of 18F-FAP-2286 PET/CT and 18F-FDG PET/CT for lung metastases, liver metastases, and bone metastases were 96.9% (94/97) and 83.5% (81/97) (P = 0.002), 100% (5/5) and 80% (4/5), and 97.2% (35/36) and 80.6% (29/36) (P = 0.042), respectively. 18F-FAP-2286 PET/CT revealed additional lesions, led to upstaging of T or M stage in 18.18% (4/22) of patients, resulting in treatment escalation in 4/22 patients. In this head-to-head comparison, 18F-FAP-2286 PET/CT demonstrated superior performance for detecting primary and metastatic ccRCC lesions and provided more accurate TNM staging, significantly impacting clinical management. Interpretation should consider limitations, notably its exploratory sample size and reliance on imaging follow-up for confirming metastases.